The general aim of this research is to investigate how people produce and comprehend speech given the real-time constraints under which they operate. We will: (1) analyse a large corpus of speech error data (utilizing special computer programs developed for this project) so as to gain information on the representation of words, the organization of the lexicon, the hierarchy of units and levels, the serial ordering of events in speech production, and the kinds of syntactic (e.g. transformational) rules which may operate in the production of utterances; and (2) conduct a number of experiments in order to gain further information concerning units, rules, and states in the production and comprehension of speech. All of the research is aimed at acquiring more data of the kind that can lead to a viable model of linguistic performance. BIBLIOGRAPHIC REFERENCES: Fromkin, V.A. (1976) 'On the formal nature of language and linguistic theories' Handbook of Perception, Vol. 7. E. Carterette and M. Friedman, Eds. Academic Press. Fromkin, V.A. (1976) 'A note on tone and the abstraction controversy' Studies in African Linguistics. Supplement 6, 47-62.